The present invention relates generally to a triangulation position detection method and device for detecting the presence of an object, such as a container, within a predetermined target window using energy radiation. More specifically, the invention is applied to a dispenser, such as a beverage and/or ice dispenser, and is incorporated into an integrated, modular dispensing valve.
The present invention evolved during continuing development and testing efforts directed toward providing an automatic dispensing valve control that is free of any physical contact with a container or by the person filing the container.
Generally, a beverage and ice dispenser consists of a mechanical push rod closing an electric switch or a manually operated push-button electric switch which actuates a dispenser to dispense product. It is thought that such dispensers transmit communicable diseases. For example, a person with such a disease who drinks out of a cup and returns to the dispenser to refill the cup must contact the cup to the dispensing push rod such that germs may be transferred from the cup to the push rod wherein the next individual to use the mechanical dispenser may come in contact with the germs by drinking from a cup subsequently placed against the same push rod.
Aside from making the dispenser control fully automatic, a main consideration in the continued development of the present invention is to provide an automatic dispensing valve which can compete economically with the prior art lever actuated dispensing valve, and the manually operated push button electric switch type valve. To be commercially successful in this market, a dispensing valve must demonstrate not only the automatic characteristics of detecting the presence of a container and activating a dispenser in response to that detection, but also deactivating the dispenser in response to the removal of the container from the dispensing position, and also demonstrate a degree of reliability at least equal to the prior art lever actuated dispensing valves and/or the manual electric switch dispensing valves, as well as economic feasibility as compared to those prior art valves.
Many attempts have been made to produce such a valve, but have fallen short of satisfying all the requirements to become commercially successful. For example, U.S. Pat. No. 4,202,287 issued to Upton, discloses a fluid dispensing control system sensing a container size with a set of photosensor and associated light sources that activate a timer in the control system for dispensing fluid for a predetermined time dependent on the container size detected. However, this system continues to dispense until a timing cycle is completed regardless of whether or not the cup is still present under the dispensing valve. Further, the amount of fluid dispensed is dependent upon preset container sizes. That is, if an establishment changes the size of its medium size cup, the preset amount of fluid dispensed for a medium size cup must be changed, or the cup will not be filled or will be overfilled.
Another type of switching device for sensing an object is disclosed in U.S. Pat. No. 4,973,834 issued to Kim. Kim discloses an optical switching device employing a frequency synchronous circuit having a synchronous stage coupled to a light sensor for synchronizing the frequency of the detection pulse train with an adjustable free running frequency. Kim requires a frequency detector to synchronize an incoming object detection pulse train with the free running frequency of the voltage controlled oscillator in a phase locked loop circuit which is adjustable externally. Such synchronization and frequency detection adds excessive cost to a dispensing valve. Further, external adjustment is not required for precise detection of moving objects in a dispenser application, and it is undesirable to require or even permit the operator of a dispensing machine to make any adjustments to an automatic dispensing valve.
Another attempt at automatic dispensing is shown in U.S. Pat. No. 4,437,499 issued to DeVale, wherein a computer controlled sensor is used for beverage dispensing. The control has a memory stored with predetermined dispensing times for small, medium, and large size cups. An operator of such a dispensing machine having such a control is required to initially program the computer with the predetermined times of dispensing for each size cup. If cup sizes are changed, the system needs to be reprogrammed. Another disadvantage to this system is that the time for filling is dependent upon whether or not ice is in the cup, and how much ice is in the cup. If the system is trained to fill a cup that is half filled with ice, each time thereafter it must have the same amount of ice in order to fill the cup to the correct level. Any deviation in the ice level will result in an overfilled or under filled condition.
Yet another type of automatic dispensing valve is disclosed in U.S. Pat. No. 5,036,892 issued to Stembridge et al., which discloses a system using ultrasonic wave energy for sensing the machine grate, the cup lip, the top of any ice in the cup, and the rising liquid level, and thereafter generates signals corresponding to the travel time of the ultrasonic energy to a control module. In order to accomplish this, Stembridge et al. changes the gain for various distance measurements. Further, Stembridge et al. has dip switches for setting the ice level. If it is determined that the actual ice height in a container is greater than that allowed by the dip switch settings, an over-ice indicator flashes and the cup detection routine begins again. The system will not activate the dispenser unless the actual ice height is less than the amount selected by the dip switches. The use of ultrasonics and extensive software and hardware results in the Stembridge et al. system being a relatively expensive dispensing valve, as compared with the lever actuated, or electric switch operated dispensing valves.
Other prior art devices include heat sensing devices which are typically used for activating water faucets in response to sensing heat generated by the operator's hand within a certain proximity of the faucet. These devices are not very accurate in determining position because of their temperature dependency. Heat sensing devices are activated when an object of a given temperature is at a certain proximity to the heat sensing device. However, if the temperature is lower than the temperature expected at the given proximity, the device will not be activated until the object with lower temperature is brought closer to the heat sensing device which shortens the expected proximity. In other words, an object's distance from the heat sensing device, to activate the device, will vary with temperature and therefore will not give precise and predictable results.
Another type of position sensing device is a light beam interrupter system in which a beam of infrared light is transmitted to a photodetector mounted opposite the infrared transmitter which transmits a steady light beam and wherein the interruption of the light beam indicates the presence of an object therebetween. For example, see U.S. Pat. No. 4,822,996 issued to Lind. This type of system is only capable of determining whether an object is present between the transmitter and the receiver and not the proximity or position of an object. In other words, this type of a detector would only function on a single axis.
An alternative transmitter and receiver arrangement was provided by Hosel, U.S. Pat. No. 5,002,102 which emits a steady beam of light from a transmitter which is reflected back to a receiver mounted adjacent the transmitter. The Hosel system requires a microcomputer with a microprocessor for calculating a distance between the transmitter/receiver and the fill level in a bin--the distance being an inverse function of the intensity of the light beam. The Hosel apparatus is based on direct reflection, that is, it simply emits light and determines how much is returned to determine the fill level distance and is therefore limited to detection on a single axis, and unless confined within a closed system such as the fiber storing bin disclosed by Hosel, the Hosel device would be susceptible to stray light sources and be inoperative in the presence of such stray light sources.
One of the disadvantages of many prior systems is that they are limited to detection on a single axis and therefore are not true position detection devices. In other words, a light beam interrupter system, for example Lind U.S. Pat. No. 4,822,996, detects an interruption in the light beam anywhere in the linear axis defined to extend from the light emitting source to the light receiving detector, and cannot differentiate the position of the interruption along that linear axis. A heat sensing device may be able to detect on multiple axes, but unless the temperature of the intruding object is constant, the point of detection varies with the temperature of the object, and therefore true position detection cannot be achieved.